Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Operating activities:
Net loss	$ (35,607)	$ (21,798)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	59,541	50,593
Deferred income taxes	(9,734)	(9,416)
Loss (gain) on asset dispositions	708	3
Equity in loss of unconsolidated affiliate, net	(162)	1,556
Inventory valuation reserves	1,234	(3)
Changes in operating assets and liabilities	(24,028)	(22,803)
Net cash used in operating activities	(8,048)	(1,868)
Investing activities:
Purchase of property and equipment	(22,761)	(49,227)
Proceeds from asset dispositions	1,453	21
Purchase of short-term investments	(284,277)	(268,525)
Purchase of restricted investments	(7,705)	0
Proceeds from sale of short-term investments	318,007	354,250
Loan to unconsolidated affiliate	(274)	0
Net cash provided by investing activities	4,443	36,519
Financing activities:
Debt issuance cost	(874)	0
Proceeds from line of credit	34,295	99,150
Payments on line of credit	(151,795)	(133,150)
Proceeds from Term Loan	(130,000)	0
Repurchase of common stock	(99)	(256)
Net cash provided by (used in) financing activities	11,527	(34,256)
Effect of exchange rate changes on cash	(239)	0
Increase in cash	7,683	395
Cash, beginning of period	8,770	2,596
Cash, end of period	16,453	2,991
Cash paid during the period for:
Interest	30,825	29,536
Income taxes	1,304	1,213
Noncash investing activities:
Other current liabilities and accrued payables related to purchase of property and equipment	$ 223	$ 21